Convergence Technologies SlideShowSIP

7/31/2019 Convergence Technologies SlideShowSIP

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ConvergenceTechnologies


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Lesson 1:Convergent Network

Traffic Protocols


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Objectives

Compare and contrast circuit-switched and packet-switched technologies, including ways that packets traversemultiple WAN links, and call and call flow descriptions

Define the Realtime Transport Protocol (RTP) and theRealtime Transport Control Protocol (RTCP)

Identify the components of Session Initiation Protocol (SIP)and describe the format of an SIP Uniform Resource Identifier (URI)

Identify the functions of signaling protocols for convergednetworks (e.g., Session Initiation Protocol [SIP], H.323, H.225,H.320, H.450, Media Gateway Control Protocol [MGCP],

Media Gateway Control [Megaco]) Compare and contrast the functions of gatekeepers,

gateways and proxies in relation to SIP and H.323 devices Compare and contrast SIP, H.323 and Megaco/MGCP


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Defining Convergence

Convergence The integration of telephony anddata technologies Integration includes:

Placing the voice network (telephony), the

video network (television, satellite) and theInternet (rich media) onto common platforms


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Smart Network and Dumb Network


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Circuit-Based vs.Convergence Calling

Circuit-switched network uses a dedicated physical pathto send and receive information

Circuit-based calls: Provide very good voice quality

May fail if the destination is busy or the network fails atany point in the connection Packet-switched network places addressing information

into data packets Convergence-based calls:

Dynamically reroute packets to other network nodes if anetwork node fails

Result in increased latency because packetization andcompression add processing time to the signal


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Transport Through aPacket-Switched Network

Packets are encapsulated in Ethernet frames At Layer 4, source and destination port

numbers are added At Layer 3, source and destination IP addresses

are added At Layer 2, source and destination MAC

addresses are added


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User Datagram Protocol

UDP header is very simple, consisting of sourceand destination port numbers, a length field, anda checksum field


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Realtime Transport Protocol (RTP)

Used to transport voice and video payloads for real-time applications Provides end-to-end delivery services Runs over both UDP and TCP

Uses even port numbers that are generallyassigned dynamically

Default port is 5004 RTP profiles define a set of codes for each type of

payload


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RTP Packets

RTP packets are encapsulated in UDP packets


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Realtime Transport ControlProtocol (RTCP)

Does not transport any data itself Partners with Realtime Transport Protocol (RTP) Monitors the media stream

Provides feedback on the Quality of Service (QoS)being provided by RTP

While RTP uses an even port number, RTCP alwaysuses the next odd port number

Default port is 5005


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Session Initiation Protocol (SIP)

Signaling protocol only does not deliver mediastreams, nor does it control the delivery of mediastreams

Initiates and manages sessions (or connections)

between 2 or more participants Primary function is to set up, modify and tear down a connection

Developed by the IETF, SIP is modeled after

Hypertext Transfer Protocol (HTTP)


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SIP Related Protocols

Session Description Protocol (SDP) Describes the characteristics of end points in a

session Multiprotocol Label Switching (MPLS)

Can provide QoS for SIP connections Resource Reservation Protocol (RSVP)

Can provide QoS for SIP connections Differentiated Services (DiffServ)

Can provide QoS for SIP connections


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SIP ports and URIs

SIP uses both UDP and TCP ports 5060 by default SIP URI takes the following format:

sip:user@host SIP URI examples:

sip:[email protected]:[email protected]:[email protected]


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SIP Components

User agents User agent client (UAC): initiates an SIP request User agent server (UAS): responds to SIP request

Servers:

Proxy: perform routing, authentication andaccounting functions

Redirect: relays information to a user agent,such as the IP address of the party to be called

Registrar: enables a client to let a proxy or redirect server know how the client can bereached


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SIP Messages

Requests INVITE ACK BYE

Cancel Options Register

Each request (except for an ACK request) requiresa response


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SIP Messages (cont'd) Responses are composed of a 3-digit Status Code

and an associated Reason Phrase


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SIP Calls

Session Invitation Consists of oneINVITE request,usually sent to anSIP proxy

A 200 OK responseis generated whenthe called partyanswers the phone

Media streams are

sent directlybetween endpoints


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H.323

Defines the following: How an audiographic call is set up across a

network How to negotiate capabilities

How to transmit data and control conferencing Which default audio and video codecs to use


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H.323 Architecture

Terminals H.323 end points Can be a stand-alone device (IP phone) or a

logical device within a PC

Includes audio and video codecs Must support H.245 for capabilities negotiation Uses Q.931 for call signaling and setup Uses H.225 RAS for communicating with

gatekeepers Must support RTP and RTCP


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H.323 Architecture (cont'd)

Gateways Connect and translate protocols between

dissimilar networks Provide protocol translation, media format

conversion and data transfer between H.323and non-H.323 networks Optional element; not required for connections

within one LAN

Required to establish connections betweenterminals in H.323 networks and terminals innetworks with different protocols


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H.323 Architecture (cont'd)

Gatekeeper functionality: Admission control Address translation Bandwidth control Zone management

Call control for point-to-point conferences Codec translation Call authorization Bandwidth and call management

Accounting and billing Call routing

Multipoint Control Unit (MCU) required whenever three or more H.323 terminals are connected


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H.225 RAS

RAS messages (requests and responses) are sent betweenend points and gatekeepers via UDP Gatekeeper messages are sent for gatekeeper discovery

(GRQ, GCF, GRJ ) Registration messages are sent for negotiating a

registration with a gatekeeper ( RRQ, RCF, RRJ ) Admission messages are requests and replies for addresstranslation ( ARQ, ACF, ARJ )

Status messages are used to monitor end point statusduring calls that are routed through a gatekeeper ( IRQ,

IRR) Disengage messages signal the end of a call ( DRQ, DCF )


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H.323 Calls

In a typical call: A client contacts a gatekeeper and requests

an address using H.225 RAS admission request(ARQ)

Gatekeeper forwards address to the client Client establishes session using H.225 Session is negotiated using H.245


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H.323 Calls (cont'd)

H.225 call signaling is used between terminals toset up and tear down a connection


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H.323 Calls (cont'd)H.245 call control signaling is used for negotiating

capabilities and master/slave determination


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Network Call Signaling (NCS)

Network Call Signaling (NCS) a protocol that createsembedded agents to use MGCP in a network


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Megaco/H.248

Enhanced version of MGCP Result of a joint effort between IETF and ITU Megaco enables the separation of call control

from media conversion

Megaco instructs an MG to connect streamscoming from outside a packet or cell datanetwork onto a packet or cell stream such asRealtime Transport Protocol (RTP) streams


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SIP vs. H.323 vs. Megaco


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Summary

Compare and contrast circuit-switched and packet-switched technologies, including ways that packets traversemultiple WAN links, and call and call flow descriptionsDefine the Realtime Transport Protocol (RTP) and theRealtime Transport Control Protocol (RTCP)

Identify the components of Session Initiation Protocol (SIP)and describe the format of an SIP Uniform Resource Identifier (URI)Identify the functions of signaling protocols for convergednetworks (e.g., Session Initiation Protocol [SIP], H.323, H.225,H.320, H.450, Media Gateway Control Protocol [MGCP],Media Gateway Control [Megaco])Compare and contrast the functions of gatekeepers,gateways and proxies in relation to SIP and H.323 devices


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Lesson 2:Implementing VoIP


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Objectives

List essential steps for qualifying a network's ability to supportconvergence (e.g., cable inspection, existing and maximumdevice capacity, replacing hubs with switches, Power over Ethernet [PoE] requirements, VLAN creation, conductingnetwork reconnaissance)

Describe the features of Telephony Application

Programming Interface (TAPI) and Messaging ApplicationProgramming Interface (MAPI) in a converged solution Implement Telephone Number Mapping (ENUM), elements

of global and private numbering plans, Local Number Portability (LNP)/Wireless LNP, end-point addressing, pathselection, calling classes, digit manipulation, overlappingnumber ranges

Identify common G.7xx codecs and their bandwidthrequirements in a converged environment (e.g., G.711,G.729, G.729a, G.726 and others)


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Objectives (cont'd)

Describe the impact of compression on voice quality, andidentify issues involved when converting voice to analogueand digital formats

Identify benefits and drawbacks of various codecs inrelation to bandwidth and voice quality

Calculate and estimate bandwidth usage for various

codecs, including considerations of overhead, connectionquality, and other factors that affect theoretical calculations(e.g., capacity planning, choosing connection speeds)

Recommend codecs for use with local/in-network/within-LAN calls, and for across WAN connections

Explain wireless convergence technologies, including DigitalEnhanced Cordless Telecommunications (DECT) and DECTlayers, Personal Wireless Telephone (PWT), Generic AccessProfile (GAP), expected ranges for interference-freecommunication, and the MHz ranges for each standard


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Objectives (cont'd)

Identify the elements of the IP Multimedia Subsystem (IMS) Explain real-time faxing, according to standards such as ITU

T.38 Explain store-and-forward faxing, according to standards

such as ITU T.37 Identify the features, benefits, problems and management

of presencing, including single sign-on, features available invarious devices

List unified message methods and benefits (e.g., fax, voice,text, video)

Identify common and essential videoconferencing codecs,

standards and practises (e.g., Moving Picture Experts Group[MPEG], Quarter Common Intermediate Format [QCIF],etc.), and choose the appropriate codecs for variousbandwidths


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Objectives (cont'd)

Summarize television/video-calling standards and practises Identify multimedia conferencing standards, including all

subsets of T.120 (e.g., T.123, T.124, T.135) Explain fundamentals of Internet Protocol television (IPTV),

including set-top box, Video on Demand (VoD), acceptedcodecs (e.g., Video Codec [VC-1])

Identify the purpose and function of voice andvideoconferencing hardware (e.g., Multipoint Control Unit[MCU], set-top box, Session Border Controller [SBC])

Compare and contrast traditional and IP-based privatebranch exchange (PBX) systems

Identify convergent terminal equipment and software,including analogue telephone adapter (ATA), single lineadapter, soft phones (WiFi, PDA, PC-based), analoguephones, time division multiplexer (TDM), protocol-specifichandsets (e.g., SIP, Megaco)


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Objectives (cont'd)

Explain power issues, including redundancy planning, Power over Ethernet (PoE)/802.3af, PoE classes, expected voltage,wattage, power sourcing equipment (PSE), powereddevices (PDs)


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Planning aConvergent Network

Major phases of an implementation plan includethese steps: Identifying expectations Determining bandwidth requirements Performing a network health check Creating a phased deployment plan


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Identifying Expectations

Identify how network(s) will be used Identify specific protocols that will be used Identify and explain potential challenges


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Determining Bandwidth Requirements

Identify current digital connection Determine bandwidth required by existing network Monitor current network performance Evaluate current network performance

Calculate additional requirements for VoIP Take wide area network (WAN) links into account Take growth into account


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Performing a Network Health Check

Check network cabling Replace hubs with Layer 2 switches Implement VLANs Prioritize VLAN traffic Check routers

Identify the entity that manages Internet router Examine current IP addressing scheme Examine Domain Name System (DNS) Examine firewall

Identify whether NAT will be implemented Identify whether VPNs must be supported Identify whether any part of the LAN will be wireless


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Creating a Phased Deployment Plan

Create a detailed, approved implementationplan Use a test network Deploy incrementally

Do not begin with the sales department


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TAPI and MAPI

Telephony Application Programming Interface(TAPI) is an API used for connecting a Windows PCto telephone services

Messaging Application Programming Interface(MAPI) is a Windows API that allows differente-mail applications to work together to distributemail


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Numbering Plans

Private numbering plansallow a company to createits own numbering system

Extensions can be createdbased on an organisationsneeds

Number plan defines theformat of telephonenumbers

Implementing VoIP involvesdesigning a numberingplan and a dial plan.

Dial plan must include rulesfor dealing with: End point addressing Path selection Calling classes

Digit manipulation Overlapping number

ranges


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Telephone Number Mapping (ENUM)

Maps E.164 telephone numbers into the DomainName System (DNS) Creates a dynamic mapping of E.164 addresses to

IP addresses

ENUM domain names are hosted in the e164.arpadomain A telephone number such as +1 (602) 555-1212

is converted into the ENUM domain name2.1.2.1.5.5.5.2.0.6.1.e164.arpa

ENUM domain name resolves to one or moreDNS NAPTR records


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G.7xx Codecs

Various codecs provide different amounts ofcompression Compression allows more voice traffic, but can

also:

Introduce delay Adversely affect voice quality Put a significant strain on CPU resources,

depending on the complexity of the algorithm

and the amount of compression


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Comparison of G.7xx Codecs


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Calculating VoIP Bandwidth Requirements

Calculations for bandwidth requirements mustfactor in: Codec, sample period and frame size Frames per packet

IP overhead Ethernet overhead Number of simultaneous calls Silence suppression

Compressed headers


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Wireless Convergence Technologies

Components Radio exchange Base stations (transceivers) Portable phones

Digital Enhanced Cordless Telecommunications (DECT) is an

ETSI standard for digital portable phones Generic Access Profile (GAP) guarantees interoperability

between any handset and any base station, regardlessof make or model

Operates in the 1880 MHz to 1900 MHz band in Europe,

Africa, Australia and Asia (except China) Operates in the following bands in North America: 902

MHz to 928 MHz, 2400 MHz to 2483.5 MHz, 5725 MHz to5850 MHz


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IP Multimedia Subsystem (IMS)

IP Multimedia Subsystem (IMS) is a network architecturedesigned to enable convergence of voice and dataapplications and various mobile network technologies

IMS architecture includes 3 layers: Connectivity layer (also called the transport layer)

composed of routers, media gateways and switches Control layer composed of network control servers that

manage call setup, modification and release Application layer (also called the service layer)

composed of application and content servers that

deliver services within the network


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Facsimile

Fax transmissions impose special demands on VoIPbecause fax standards were designed for circuit-switched connections

T.30 standardizes the way in which faxes are sentacross standard circuit-switched telephone lines

T.38 designed for real-time fax transmissions over an IP network

T.37 designed for store-and-forward faxtransmission over an IP network


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Presencing

Presence information is a status indicator thatconveys a persons willingness and ability toengage in communications

Presencing can span different communicationchannels

Multiple Points of Presence (MPOP) describes howmultiple communications devices can combinestate to provide a multidimensional view of ausers availability status

Presencing requires collaboration among anumber of devices and the presence services withwhich each of them is connected

Presencing raises privacy concerns


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Unified Messaging

In unified messaging (UM), all messaging mediacan come together in the form of a unifiedmailbox and/or alert service

Unified messaging offers Single delivery Single repository Single access Single notification


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Video Services

Video codecs and standards include: H.261 Common Intermediate Format (CIF)

Quarter CIF (QCIF) Sub Quarter CIF (SQCIF) 4CIF 16CIF

H.263 Moving Picture Experts Group (MPEG)

MPEG-1

MPEG-2/H.262 MPEG-4 H.264/MPEG-4 Advanced Video Coding (AVC) Realtime Streaming Protocol (RTSP)


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T.120 Multimedia Conferencing Standards

Key features: Support for real-time communication between

two or more entities Support for application sharing, electronic

whiteboarding, file exchange and chat Support for interoperability between end points

from multiple vendors Support for a broad range of transport options

Co-existence with other standards


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T.120 Architecture

Additional protocols: T.128: Multipoint application sharing T.134: Text chat application entity

T.135: User-to-reservation system transactions with T.120conferences T.136: Remote device control application protocol T.137: Virtual meeting room management services and

protocol


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Internet Protocol TV (IPTV)

Internet Protocol TV (IPTV) can include Live broadcast (uses Internet Group Messaging

Protocol [IGMP] version 2) Video on Demand (uses Realtime Streaming

Protocol [RTSP]) Requires a set-top box or PC to receive content

from a media server Common codecs include: H.264/MPEG-4 AVC,

MPEG-2, VC-1


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Common Convergence Devices

Videoconferencing hardware Multipoint Control Unit (MCU) Session Border Controller (SBC)

IP PBX or traditional PBX

Terminal equipment VoIP phones Digital phones analogue telephones and adapters Soft phones Single line adapter Time division multiplexer


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Power Issues for Convergent Networks

Redundant power Uninterruptible power supply (UPS)

Power over Ethernet (PoE) Power Sourcing Equipment (PSE) provides power Powered Devices (PD) use the power provided

Maximum power supplied is 15.4 watts at 48 volts Five power classes (0-4) Two power modes (Mode A and Mode B)

PSE capable of determining the mode a PD uses

Injector supplies power into the appropriate wires of theEthernet cable Deployment of PoE requires a power budget to ensure

that PSE can supply sufficient power to all PDs


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Summary

List essential steps for qualifying a network's ability to supportconvergence (e.g., cable inspection, existing and maximumdevice capacity, replacing hubs with switches, Power over Ethernet [PoE] requirements, VLAN creation, conductingnetwork reconnaissanceDescribe the features of Telephony ApplicationProgramming Interface (TAPI) and Messaging ApplicationProgramming Interface (MAPI) in a converged solutionImplement Telephone Number Mapping (ENUM), elementsof global and private numbering plans, Local Number Portability (LNP)/Wireless LNP, end-point addressing, pathselection, calling classes, digit manipulation, overlapping

number rangesIdentify common G.7xx codecs and their bandwidthrequirements in a converged environment (e.g., G.711,G.729, G.729a, G.726 and others)


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Summary (cont'd)

Describe the impact of compression on voice quality, andidentify issues involved when converting voice to analogueand digital formatsIdentify benefits and drawbacks of various codecs inrelation to bandwidth and voice qualityCalculate and estimate bandwidth usage for various

codecs, including considerations of overhead, connectionquality, and other factors that affect theoretical calculations(e.g., capacity planning, choosing connection speeds)Recommend codecs for use with local/in-network/within-LAN calls, and for across WAN connectionsExplain wireless convergence technologies, including DigitalEnhanced Cordless Telecommunications (DECT) and DECTlayers, Personal Wireless Telephone (PWT), Generic AccessProfile (GAP), expected ranges for interference-freecommunication, and the MHz ranges for each standard


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Summary (cont'd)

Identify the elements of the IP Multimedia Subsystem (IMS)Explain real-time faxing, according to standards such as ITUT.38Explain store-and-forward faxing, according to standardssuch as ITU T.37Identify the features, benefits, problems and management

of presencing, including single sign-on, features available invarious devicesList unified message methods and benefits (e.g., fax, voice,text, video)Identify common and essential videoconferencing codecs,standards and practises (e.g., Moving Picture Experts Group[MPEG], Quarter Common Intermediate Format [QCIF],etc.), and choose the appropriate codecs for variousbandwidths


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Summary (cont'd)

Summarize television/video-calling standards and practisesIdentify multimedia conferencing standards, including allsubsets of T.120 (e.g., T.123, T.124, T.135)Explain fundamentals of Internet Protocol television (IPTV),including set-top box, Video on Demand (VoD), acceptedcodecs (e.g., Video Codec [VC-1])

Identify the purpose and function of voice andvideoconferencing hardware (e.g., Multipoint Control Unit[MCU], set-top box, Session Border Controller [SBC])Compare and contrast traditional and IP-based privatebranch exchange (PBX) systemsIdentify convergent terminal equipment and software,including analogue telephone adapter (ATA), single lineadapter, soft phones (WiFi, PDA, PC-based), analoguephones, time division multiplexer (TDM), protocol-specifichandsets (e.g., SIP, Megaco)


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Summary (cont'd)

Explain power issues, including redundancy planning, Power over Ethernet (PoE)/802.3af, PoE classes, expected voltage,wattage, power sourcing equipment (PSE), powereddevices (PDs)


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Lesson 3:Traffic, Troubleshooting

and Security


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Objectives

Define latency, jitter and wander Implement methods for reducing or eliminating latency, jitter

and wander (e.g., implementing a jitter buffer, implementingQoS, traffic shaping, VLANs)

Explain the impact of large frames on real-timecommunications

Identify factors that affect the bandwidth of voice andvideo calls on convergent networks (e.g., latency, protocolincompatibility, MTU, codec choice, compression, QoSissues, packet reordering, loss of feature set)

Use accepted industry standards such as the Mean OpinionScore (MOS) to determine voice and video quality, includingMOS for popular codecs, standard MOS numbers, R-valueand subjective video quality


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Objectives (cont'd)

Identify common network bottlenecks in convergentnetworks, including solutions (e.g., monitoring network devices and protocols, creating a baseline, changingconfiguration, upgrading hardware)

Analyze traffic in a convergent network and resolve

problems using a packet sniffer, monitoring software, andhardware solutions

Troubleshoot convergent communications over wirelessnetworks

Identify problems in contacting emergency services through

convergent networks Parse a Call Detail Record (CDR) and list relevant entries


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Objectives (cont'd)

Identify types and effects of attacks in convergent networks,including man-in-the-middle attacks (e.g., packet sniffing,TCP connection hijacking, registration hijacking), voice mailcompromises, viruses, brute-force and dictionary attacks,zero-day attacks, illicit servers, toll fraud and unsolicited calls

Define denial-of-service (DOS) and distributed DOS (DDOS)

attacks, and identify ways to counteract them, includingcommon traffic types used (e.g., SYN, UDP or ICMP flood),reconfiguring core upstream routers, using alternative sites,intentional and unintentional DOS

Explain the practise and impact of VLAN hopping Explain the significance and impact of MAC address

movements, additions and changes Identify types of intrusion detection (e.g., host-based,

network-based, defining effective signatures, proactivedetection)


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Objectives (cont'd)

Back up, upgrade and scan systems to thwart attacks,including backup types, system patches, service packs,firmware upgrades, optimal backup schedule


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VoIP Variables

VoIP variables conditions that cause problems invoice communications

VoIP variables include: Delay the amount of wait time between the

time a signal is sent and received Latency the amount of time required for data

to be transmitted across a network Jitter variability in the arrival rate of data

packets transmitted over a network Wander variability of more than one second

in the arrival rate of data packets transmittedover a network (long-term jitter)


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Delay Fixed delays

Propagation delay caused by the distance betweenthe request and the server fulfilling the request Serialization delay the time required to physically place

voice call bits on a trunk line End point processing delay caused by compressing/

decompressing and encoding/decoding data Packetization delay the time required to place digital

traffic into a particular medium Variable delays

Queuing delay the time packets wait for other packetsto be placed onto a trunk line

Router processing delay the time required for a router to apply QoS settings, or to process packets that havearrived out of order


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Latency

Latency results when multiple delays occur The most significant source of latency is the digital

signal processing that occurs in gateways androuters

Round-trip latency is the total delay experiencedby two users on a phone call

Round-trip latency in the PSTN is typically less than150 milliseconds, except on international calls

ITU recommends that for good voice quality inVoIP calls, one-way latency must not exceed 150milliseconds


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Jitter

Jitter occurs when packets in a voice transmissiontake different paths over a network, causing themto arrive out of sequence

A jitter buffer can correct this variability byproviding a space in memory that allows packetresequencing


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Packet Handling in the Enterprise

A chief cause of delay and jitter is queuing at therouter

By default, routers process queues on a first in firstout (FIFO) basis

Implementing QoS on routers improves voicequality

Convergent QoS technologies include: Creating VLANS

Assigning prioritization Setting IP precedence values Employing traffic-shaping algorithms


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Wander

Wander is due to synchronization problems in thenetwork clocks used to control transmissions

When wander is detected, the signal must bereclocked, or synchronized, at the next network element to avoid propagating the wander activity

The Network Time Protocol (NTP) ensures thatsystems are accurate to within milliseconds

NTP servers belong to two strata: Stratum 1 clocks that are the most accurate;

often GPS-enabled timekeeping systems Stratum 3/3E VoIP gatekeepers, gateways

and PBXs


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Other Throughput Considerations

Additional factors that affect the quality of voicetransmissions include: Choice of codec Complexity of compression algorithm

Lack of QoS support on the network Overutilization of routers Packet reordering (caused by congestion and

queuing at routers)

Protocol and codec incompatibility MTU setting Loss of feature set

Connection QoS:


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Connection QoS:Using Multiple Connections

Connection QoS ensures that the gateway canprotect calls from network problems in severalways, including: Trunk busy-out

Alternative gateway selection Fallback to the PSTN The gateway prevents a trunk from servicing a call

if:

The IP network fails The gateway detects an internal problem

( )


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Mean Opinion Score (MOS)

MOS is an industry standard numericalmeasurement of voice quality

R l


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R-value

R-value is another industry standard for measuringvoice quality

R-values are derived from direct measurements ofequipment and traffic parameters

R-value score ranges from 1 (worst) to 100 (best) One MOS point is roughly equal to 20 R-value

points, but the correlation is not linear

f l d


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Mean Opinion Scores for Popular AudioCodecs


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Maintaining and TroubleshootingConvergent Networks

Monitoring is an important aspect of maintainingconvergent networks

The first step in monitoring is establishing a baseline A baseline is a record of normal network

activity that serves as an example for comparing future network activity

E bli hi B li


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Establishing a Baseline

Baseline measurement statistics should includedata on: Traffic analysis/end-to-end performance

Identifies latency, percentage of packet lossand link utilization

Tools include: ping and traceroute, andhardware monitoring mode

Device performance

Identifies factors such as CPU and memoryusage

D i C fi ti


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Device Configuration

Device configuration directly affects the performance ofconvergent networks

Check configurations of Switches

Ensure VLANs are properly configured

Ensure proper communication mode (full-duplex, half-duplex, auto-negotiation) settings on switch ports End points

Ensure each end point has a valid IP address Ensure that communication mode on NIC is set

properly Install firmware or software updates as they become

available

Troubleshooting Convergence in


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g gWireless Networks

In wireless networks, points for troubleshooting include: Access points (APs):

Should support enterprise-level QoS Should provide overlapping coverage Should be deployed in sufficient number

Should be able to reject calls when becomingoverloaded Should support roaming

Environment Check for sources of interference

Handsets Ensure proper configurations (for example, encryption

keys) Install available updates/upgrades

C ll D t il R d


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Call Detail Records

Call Detail Records include information about thethe following call details: Time Date

Call duration Number dialed Caller ID information Extension

Line/trunk location Cost Call completion status

S it i C g t N t k


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Security in Convergent Networks

Security is a set of procedures designed to protecttransmitted and stored information, as well asnetwork resources

In convergent networks, security includespreventing: Call interception Phone fraud Network attacks

Protocol Review


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Protocol Review

Inherent weaknesses in IPv4 include: Transmission Control Protocol (TCP) handshake

often manipulated by hackers Internet Protocol (IP) does not sign or encrypt

packets, and packets are easily manipulated User Datagram Protocol (UDP) often used to

conduct scans of systems, and UDP packetscan be forged to wage distributed denial-of-service attacks

Address Resolution Protocol (ARP) does notauthenticate the hosts it resolves and is subjectto ARP cache poisoning

Overview of Network Attacks


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Overview of Network Attacks

Network attacks include:

Spoofing attacks IP spoofing ARP spoofing DNS spoofing

Man-in-the-middle (hijacking) attacks Password sniffing Connection termination Connection hijacking Packet insertion Poisoning

Password-guessing attacks Brute-force attacks Dictionary attacks

Malicious Code


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Malicious Code

Types of malicious code include: Viruses Worms Illicit servers

Trojan horses To avoid malicious code, use:

Virus and worm protection Application management and testing

Configuration management File signature checking software

Denial of Service (DOS) Attacks


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Denial-of-Service (DOS) Attacks

Purpose of a denial-of-service attack is to: Crash a server and make it unusable to

everyone Assume the identity of the system being

crashed

Install a Trojan Flooding is the process of sending an

overwhelming number of packets to a system Flooding techniques include:

SYN flood Ping flood UDP flood

Distributed Denial-of-Service (DDOS)


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Distributed Denial-of-Service (DDOS)Attacks

Involve the cooperation of several systems to wage acoordinated attach that generates an overwhelmingamount of network traffic

DDOS attacks involve: A controlling application

An illicit service A zombie A target

DOS and DDOS attacks can be diagnosed by:

Using a packet sniffer to view traffic Using the netstat command to view connections Using intrusion-detection systems

VLAN Hopping


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VLAN Hopping

VLAN hopping is an attack in which a hacker intercepts packets as they are sent from one VLANto another on a trunk

To avoid VLAN hopping: Disable autotrunking Remove the native VLAN setting (VLAN 1) from

any trunk port

MAC Address Movements


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MAC Address Movements

Sudden changes in MAC addresses, such as twosystems suddenly exchanging IP addresses, canindicate that someone is attempting to poison theARP cache

Monitoring the ARP cache with a tool such asArpwatch can guard against ARP spoofing

Intrusion Detection


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Intrusion Detection

Intrusion detection strategies rely on:

Signature detection Anomaly detection (less common)

IDS applications require a current signature database IDS application types are:

Host-based Captures traffic only on host, not on the network wire

Network-based Does not capture traffic on switched networks Port mirroring enables captures and monitoring on

switched networks

Maintaining Your Networks


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Maintaining Your Networks

Essential tasks for maintaining a convergent network include:

Scan systems regularly to detect unusual behaviour Upgrade equipment as necessary Install system patches and service packs Keep antivirus files current

Install firmware upgrades Perform regular backups

Full Differential Incremental

Verify that backups are successful Ensure careful (off-site) storage of backup media Choose an optimal backup schedule

Summary


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Summary

Define latency, jitter and wander Implement methods for reducing or eliminating latency, jitter and wander (e.g., implementing a jitter buffer, implementingQoS, traffic shaping, VLANs)Explain the impact of large frames on real-time

communicationsIdentify factors that affect the bandwidth of voice andvideo calls on convergent networks (e.g., latency, protocolincompatibility, MTU, codec choice, compression, QoSissues, packet reordering, loss of feature set)

Use accepted industry standards such as the Mean OpinionScore (MOS) to determine voice and video quality, includingMOS for popular codecs, standard MOS numbers, R-valueand subjective video quality

Summary (cont'd)


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Summary (cont d)

Identify common network bottlenecks in convergent

networks, including solutions (e.g., monitoring network devices and protocols, creating a baseline, changingconfiguration, upgrading hardware)Analyze traffic in a convergent network and resolveproblems using a packet sniffer, monitoring software, and

hardware solutionsTroubleshoot convergent communications over wirelessnetworksIdentify problems in contacting emergency services throughconvergent networksParse a Call Detail Record (CDR) and list relevant entries

Summary (cont'd)


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Summary (cont d)

Identify types and effects of attacks in convergent networks,

including man-in-the-middle attacks (e.g., packet sniffing,TCP connection hijacking, registration hijacking), voice mailcompromises, viruses, brute-force and dictionary attacks,zero-day attacks, illicit servers, toll fraud and unsolicited callsDefine denial-of-service (DOS) and distributed DOS (DDOS)

attacks, and identify ways to counteract them, includingcommon traffic types used (e.g., SYN, UDP or ICMP flood),reconfiguring core upstream routers, using alternative sites,intentional and unintentional DOSExplain the practise and impact of VLAN hopping

Explain the significance and impact of MAC addressmovements, additions and changes

Summary (cont'd)


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Summary (cont d)

Identify types of intrusion detection (e.g., host-based,

network-based, defining effective signatures, proactivedetection)Explain the practise and impact of VLAN hoppingBack up, upgrade and scan systems to thwart attacks,including backup types, system patches, service packs,firmware upgrades, optimal backup schedule

Convergence Technologies


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Convergence Technologies

Convergent Network Traffic ProtocolsImplementing VoIPTraffic, Troubleshooting and Security

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